Electrochromism of Methylviologen (Paraquat)

Aristov, N.; Habekost, Achim

doi:10.12691/wjce-3-4-1

Cited by 65 publications

(36 citation statements)

References 24 publications

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“…The solution was observed to change from colorless (MV 2+ ) to brilliant purple (MV + ) near the cathode upon the application of 1 V, consistent with the reported value of the redox potential for the MV 2+ + e − → MV + reaction of~0.7 V (Figure 2) [52][53][54]. A similar color change was observed for a slurry of lysozyme crystals containing methyl viologen (Figure 4).…”

Section: Resultssupporting

confidence: 84%

“…However, after several minutes, the solution transitioned from purple to clear, as MV + was further reduced to MV 0 (Figure 4). Again, this result was expected, based on the reported redox potential for the MV + + e − → MV 0 reaction [52][53][54]. The pale yellow color of the MV 0 was difficult to discern compared to the fully oxidized MV 2+ species, because of the small path length in our microfluidic devices.…”

Section: Resultssupporting

confidence: 73%

“…In the presence of oxygen, methyl viologen is present as fully oxidized MV 2+ , resulting in a colorless solution. The partially oxidized MV + species is a brilliant purple, while the fully reduced, neutral MV 0 is typically light yellow [52][53][54]. To test the ability of our graphene-based devices to conduct electricity and drive redox chemistry, 10 µL of fully oxidized methyl viologen was placed onto a patterned graphene electrode.…”

Section: Redox Chemistry Testingmentioning

confidence: 99%

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A Graphene-Based Microfluidic Platform for Electrocrystallization and In Situ X-ray Diffraction

et al. 2018

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Here, we describe a novel microfluidic platform for use in electrocrystallization experiments. The device incorporates ultra-thin graphene-based films as electrodes and as X-ray transparent windows to enable in situ X-ray diffraction analysis. Furthermore, large-area graphene films serve as a gas barrier, creating a stable sample environment over time. We characterize different methods for fabricating graphene electrodes, and validate the electrical capabilities of our device through the use of methyl viologen, a redox-sensitive dye. Proof-of-concept electrocrystallization experiments using an internal electric field at constant potential were performed using hen egg-white lysozyme (HEWL) as a model system. We observed faster nucleation and crystal growth, as well as a higher signal-to-noise for diffraction data obtained from crystals prepared in the presence of an applied electric field. Although this work is focused on the electrocrystallization of proteins for structural biology, we anticipate that this technology should also find utility in a broad range of both X-ray technologies and other applications of microfluidic technology.

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Section: Resultssupporting

confidence: 84%

Section: Resultssupporting

confidence: 73%

Section: Redox Chemistry Testingmentioning

confidence: 99%

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A Graphene-Based Microfluidic Platform for Electrocrystallization and In Situ X-ray Diffraction

et al. 2018

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“…Scan‐rate‐dependent CV data are shown in Figure S2. The peak separations were ∼30 mV and did not increase with scan rate suggesting a completely reversible two‐electron transfer redox reaction …”

Section: Resultsmentioning

confidence: 99%

Repurposing the Industrial Dye Methylene Blue as an Active Component for Redox Flow Batteries

Kosswattaarachchi

Cook

2018

ChemElectroChem

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Methylene blue is a common component of industrial wastewater in the textile industry. The redox properties of this environmentally damaging molecule make it suitable for use in the electrolyte solutions of aqueous redox flow batteries. Here, we carry out electrochemical analyses of aqueous methylene blue solutions to establish the dye as a pH tuneable, two‐electron redox transfer agent with fast transfer kinetics. Galvanostatic charge‐discharge experiments demonstrated ∼100 % coulombic efficiency for 50 cycles over seven days. Cycling performance was dependent on the membrane separator used. Cells containing an AMI‐7001 membrane showed a capacity decay with the state‐of‐charge falling to 56 % due to dye adsorption. Nafion NE1035 showed no adsorption nor membrane crossover. The combination of chemical and redox stability, and fast kinetics motivate the recycling of methylene blue wastewater as the basis for flow battery electrolyte solutions.

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“…An opposite behavior is observed in the material with a higher Fe wt% (or lower Ru wt%, RuFe-2), where the intensity of peaks does not decrease significantly upon increasing the number of cycles (30th). Because of the peak-to-peak separations (ΔE p =0.050 V and 0.100 V for RuFe-1 and RuFe-2, respectively) and the current density ratios (j p,a /j p,c =1.9 and 1.6 for RuFe-1 and RuFe-2, respectively), as there is a transfer of 2 electrons this parameters do not correspond to a fast reversible system, the iron electrochemical process could be considered quasi-reversible on these materials [31].…”

Section: Structural and Morphological Characterizationmentioning

confidence: 99%

Oxygen reduction and hydrogen oxidation reactions on Ru-Fe electrocatalyst synthesized by a microwave-assisted synthesis

Su-Gallegos

Magallón-Cacho

Borja-Arco

et al. 2020

Mater. Res. Express

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In this work, the oxygen reduction reaction in the absence or presence of 2.0 mol l −1 methanol and the hydrogen oxidation reaction are studied on RuFe electrocatalyst synthesized by a microwave thermal heating method in water as reaction medium. The electrocatalysts were morphologically and structurally typified by scanning electron microscopy and by x-ray diffraction, respectively. Three crystalline phases were found: Ru, Fe 2 O 3 and Fe(OH) 3 ·(H 2 O) x (Bernalite). Functional tests were performed by convective (rotating disk electrode) and non-convective (linear sweep voltammetry and cyclic voltammetry) electrochemical techniques in 0.5 mol l −1 H 2 SO 4 . Both RuFe electrocatalysts show interesting electrochemical activities since they can carry out both the oxygen reduction reaction and the hydrogen oxidation reaction.

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Electrochromism of Methylviologen (Paraquat)

Cited by 65 publications

References 24 publications

A Graphene-Based Microfluidic Platform for Electrocrystallization and In Situ X-ray Diffraction

A Graphene-Based Microfluidic Platform for Electrocrystallization and In Situ X-ray Diffraction

Repurposing the Industrial Dye Methylene Blue as an Active Component for Redox Flow Batteries

Oxygen reduction and hydrogen oxidation reactions on Ru-Fe electrocatalyst synthesized by a microwave-assisted synthesis

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